Vertical stent cutting process

ABSTRACT

A system and method for processing a tubular member for producing a medical device, wherein the tubular member is oriented in a longitudinally vertical position during processing.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] Not Applicable

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0002] Not Applicable

BACKGROUND OF THE INVENTION

[0003] A stent is a radially expandable endoprosthesis which is adaptedto be implanted in a body lumen. Stents are typically used in thetreatment of atherosclerotic stenosis in blood vessels and the like toreinforce body vessels and to prevent restenosis following angioplastyin the vascular system. They have also been implanted in urinary tracts,bile ducts and other bodily lumen. They may be self-expanding orexpanded by an internal radial force, such as when mounted on a balloon.

[0004] Delivery and implantation of a stent is accomplished by disposingthe stent about a distal portion of the catheter, percutaneouslyinserting the distal portion of the catheter in a bodily vessel,advancing the catheter in the bodily lumen to a desired location,expanding the stent and removing the catheter from the lumen. In thecase of a balloon expandable stent, the stent is mounted about a balloondisposed on the catheter and expanded by inflating the balloon. Theballoon may then be deflated and the catheter withdrawn. In the case ofa self-expanding stent, the stent may be held in place on the cathetervia a retractable sheath. When the stent is in a desired bodilylocation, the sheath may be withdrawn allowing the stent to self-expand.

[0005] In the past, stents have been generally tubular but have beencomposed of many configurations and have been made of many materials,including metals and plastic. Ordinary metals such as stainless steelhave been used as have shape memory metals such as Nitinol and the like.Stents have also been made of bio-absorbable plastic materials. Stentshave been formed from wire, tube stock, etc. Stents have also been madefrom sheets of material which are rolled.

[0006] A number of techniques have been suggested for the fabrication ofstents from sheets and tubes. One such technique involves laser cuttinga pattern into a sheet of material and rolling the sheet into a tube ordirectly laser cutting the desired pattern into a tube. Other techniquesinvolve cutting a desired pattern into a sheet or a tube via chemicaletching or electrical discharge machining.

[0007] Laser cutting of stents has been described in a number ofpublications including U.S. Pat. No. 5,780,807 to Saunders, U.S. Pat.No. 5,922,005 to Richter and U.S. Pat. No. 5,906,759 to Richter. Otherreferences wherein laser cutting of stents is described include: U.S.Pat. No. 5,514,154, U.S. Pat. No. 5,759,192, U.S. Pat. No. 6,131,266 andU.S. Pat. No. 6,197,048.

[0008] An example of a conventional laser for cutting a stent is ahighly focused pulsed Nd:YAG laser which has a pulse duration in therange of approximately 0.1 to 20 milliseconds. This is a long pulse timefor cutting and characteristically produces a relatively large melt zoneand heat affected zone (HAZ) on the metal. The conventional lasercutting process typically results in the formation of melt dross on theinside edge of the cut tube. This dross must be cleaned off insubsequent processes.

[0009] Past laser cutting systems typically mount the tube to be cutfrom a spindle shaft in a horizontal orientation wherein the laser ismounted perpendicular to the longitudinal axis of the tube in a downwardlooking configuration. Such a horizontal orientation of the stent tubehas many drawbacks.

[0010] For example, as the tube is being cut, dross and other debris mayaccumulate in the tube interior. This requires a stream of water toflush the tube to wash away the debris. The horizontal orientation ofthe tube additionally exacerbates the problem of ridding debris from thetube as debris must be actively driven out the open end of the tube.This necessitates the flushing stream be applied with significantpressure to ensure that debris does not clog the tube end.

[0011] Another more serious drawback is that in some cases, particularlyin longer tubes, the tube may tend to bow as a result of gravity. Suchbowing may interfere with the precise nature of the stent cuttingprocess, resulting in cutting errors or more significant damage to thetube/stent. In addition, as the tube is rotated during cutting, anybowing of the tube will cause the unsecured end of the tube to oscillateresulting in excess strain being placed on the tube, and potentiallyleading to improper cutting and/or the formation of cuttingimperfections.

[0012] In light of the above a need exists to provide a lasercutting/processing system wherein the potential for tube bowing and tubeoscillation is minimized or removed completely, and where cutting debrissuch as melt dross is more easily and consistently removed from the tubeduring processing.

[0013] All US patents and applications and all other published documentsmentioned anywhere in this application are incorporated herein byreference in their entirety.

[0014] Without limiting the scope of the invention a brief summary ofsome of the claimed embodiments of the invention is set forth below.Additional details of the summarized embodiments of the invention and/oradditional embodiments of the invention may be found in the DetailedDescription of the Invention below.

[0015] A brief abstract of the technical disclosure in the specificationis provided as well only for the purposes of complying with 37 C.F.R.1.72. The abstract is not intended to be used for interpreting the scopeof the claims.

BRIEF SUMMARY OF THE INVENTION

[0016] The present invention is directed to a variety of embodiments. Inat least one embodiment the invention is directed to a system forcutting, etching and/or otherwise processing a hollow metal tube formanufacturing a stent, wherein the tube/stent is positioned with itslongitudinal axis in a vertical orientation relative to the ground. Suchvertical orientation allows gravity to help maintain at least the freeend the tube/stent in a stable position through out the cutting process.

[0017] In some embodiments of the invention the tube being cut may be atleast partially, and even entirely, constructed of a polymer.

[0018] Vertical orientation of the tube also encourages dross and otherdebris formed during cutting to be gravitationally drawn out of and awayfrom the tube continuously through out the laser cutting process.

[0019] In some embodiments a stream of fluid or other media may bepoured or injected through the lumen of the tube to cool the tube,provide increased stability to the tube, and/or assist in removingdebris from the tube.

[0020] As indicated above, in some embodiments the tube is cut ormachined by a laser, such as a YAG, IR, UV, diode, CO₂ or other type oflaser. In at least one embodiment the stent cutting system utilizes ahybrid laser/water jet mechanism to direct laser energy to the tubethrough a column of fluid such as water. Such laser/water jet systemsare known and are commercially available from SYNOVA Inc., of Lausanne,Switzerland. The SYNOVA system utilizes a laser beam that is containedwithin a water jet as a parallel beam, similar in principle to anoptical fiber.

[0021] In some embodiments the flow of fluid or other media through thetube lumen will help protect the tube interior from potential damagecaused by the cutting laser by disrupting the water jet and laser energytransmitted therethrough. Such use of a media flow in conjunction with alaser/water jet hybrid system is described in greater detail in aco-pending Patent Application filed simultaneously herewith entitledTubular Cutting Process and System.

[0022] In some embodiments a collar or guide defines a chamber which atleast a portion of the free end of the tube is inserted. The guide maybe utilized to stabilize and/or minimize oscillations or otherdisruptive movement of the free end of the tube during the cuttingprocess.

[0023] In some embodiments a nozzle or other attachment sprays a fluidonto and/or through the tube.

[0024] Where a fluid is sprayed or otherwise directed onto or throughthe tube, the fluid may be act as an oxidizer, cleaner, polishing agent,pretreatment or other solution. In some embodiments the fluid aids inremoving debris from the tube during processing.

[0025] In various embodiments the guide and the chamber defined thereby,may have a variety of shapes and sizes to accommodate tubes of differentconfigurations. In at least one embodiment the guide is split, having atleast two portions. The portions may be variably positioned to allow theguide to receive a wide variety of tube diameters therein.

[0026] In at least one embodiment the guide is one or more coils of aformed wire(s) which are disposed about at least a portion of the tube.

[0027] These and other embodiments which characterize the invention arepointed out with particularity in the claims annexed hereto and forminga part hereof. However, for a better understanding of the invention, itsadvantages and objectives obtained by its use, reference should be madeto the drawings which form a further part hereof and the accompanyingdescriptive matter, in which there is illustrated and describedembodiments of the invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

[0028] A detailed description of the invention is hereafter describedwith specific reference being made to the drawings.

[0029]FIG. 1 is a side view of an embodiment of the invention.

[0030]FIG. 2 is a cross-sectional view of an example of a guidemechanism.

[0031]FIG. 3 is a perspective view of an example of a variable diameterguide mechanism.

[0032]FIG. 4 is a top down cross-sectional view of the guide mechanismof FIG. 3 shown in use with a tube of a first diameter.

[0033]FIG. 5 is a top down cross-sectional view of the guide mechanismof FIG. 3 shown in use with a tube of a second diameter.

[0034]FIGS. 6 and 7 show an example shape of a guide mechanism.

[0035]FIGS. 8 and 9 show an example shape of a guide mechanism.

[0036]FIG. 10 shows another example of a guide mechanism.

DETAILED DESCRIPTION OF THE INVENTION

[0037] While this invention may be embodied in many different forms,there are described in detail herein specific preferred embodiments ofthe invention. This description is an exemplification of the principlesof the invention and is not intended to limit the invention to theparticular embodiments illustrated.

[0038] For the purposes of this disclosure, like reference numerals inthe figures shall refer to like features unless otherwise indicated.

[0039] As indicated above the present invention is directed to a varietyof embodiments. In at least one embodiment, shown in FIG. 1, theinvention is directed to a mechanism (system), indicated generally at10, for processing and/or cutting a hollow tubular body 12 into amedical device such as a stent.

[0040] In the embodiment shown, the hollow tubular body 12 may be anytype of tube suitable for laser processing and/or cutting. Such a tube12 may be a tubular member suitable for the construction of a stent,graft, stent-graft, vena cava filter, hypo tube, catheter or componentthereof, or any other device suitable for insertion and/or implantationinto a body lumen. Where the tube 12 is intended for the construction ofa stent, the tube 12 will typically be at least partially constructedfrom a metal such as stainless steel, nickel, titanium, palladium, gold,tantalum, or any other metal or alloy thereof. However, other materialsmay be alternatively or additionally used, such as one or more polymers.In at least one embodiment tube 12 is constructed of a nickel-titaniumalloy such as nitinol.

[0041] Where tube 12 is at least partially constructed from one or morepolymer substances, the substances may include, but are not limited tothe following examples: polyester/polyether elastomers such as Arnitel™available from DSM Engineering; polyurethane-polyether polymers, such asTecothane™ and/or Tecoplastm both being available from Thermedics, Inc.;polyester-polyurethanes, such as Pellethane™ sold by Dow Chemical;polyester-polyurethanes, such as Estane sold by BF Goodrich; polyetherblock amides (PEBA), such as Pebax™ available from Elf Atochem;styrene15 butadien-styrene triblock copolymers, such as Kraton™ sold byShell Chemical company; styrenic block copolymers; polyurethanes;silicone rubber; natural rubber; copolyesters; polyamides; EPDMrubber/polyolefin; nitril rubber/PVC; fluoroelastomers; butyl rubber;epichlorohydrin; block copolymers; polyethylene terephthalate (PET);polyethylene naphthalate (PEN); polybutylene terephthalate (PBT);polytrimethylene terephthalate (PTT); poly lactic acid (PLA);fluoropolymers; polyolefins; polystyrene; polyvinyl chloride (PVC);acrylonitrile-butadiene-styrene polymers; polyacrylonitrile;polyacrylate; vinyl acetate polymer; cellulose plastics; polyacetal;polyethers; polycarbonates; polyphenylene sulfide;polyarylethersulfones; polyaryletherketones; polytetrafluoroethylene;polyamide copolymer, such as MXD6™ available from Mitsubishi GasChemical Co. or Cristamid™ available from Atofina; shape-memorypolymers; liquid crystal polymers; bio-absorbable polymers; radiopaquepolymers; MRI-visible polymers; etc.

[0042] Tube 12 may also include various coatings or surface materials,such as drug and/or drug vectors, lubricants, etc.

[0043] Regardless of the particular composition or the type of materialused for tube 12, in accordance with the present invention the tube isprocessed or cut while positioned in a substantially longitudinalvertical orientation, such as is shown. Longitudinally vertical positionas used herein means that tube is positioned relative to the ground suchthat the longitudinal axis of the tube is substantially perpendicular tothe plane of the ground.

[0044] Vertical orientation of the tube during the cutting processprovides an increase in processing efficiency, particularly by employinggravity to prevent tube bowing, encourage dross removal from the tube,and reduce oscillations at the free end of the tube as it rotates.

[0045] In the embodiment shown the tube 12 is mounted at a first end 14to a affixing device 16 of a rotary spindle or shaft 18 of a processingmechanism. During the cutting process the shaft maybe rotated as well asmoved vertically in an upwards and/or downwards direction according to apredetermined pattern. The movement of the shaft 18 causes the tube 12to be moved relative to a laser or other cutting mechanism 20.

[0046] In some embodiments the laser 20 may be moveable relative to thetube 12. In some embodiments the laser 20 may be capable of directinglaser energy, indicated by arrow 22, to the tube 12 from multiple anglesand/or directions.

[0047] In the embodiment shown in FIG. 1, laser 20 directs laser energy22 to the tube 12. As tube 12 is moved via the predetermined movementpattern of shaft 18 the laser energy 22 cuts a corresponding patterninto the tube 12. As indicated above laser 20 may be any type of laser,such as a YAG, diode, IR, UV, CO₂, or other type of laser. In at leastone embodiment laser 20 is a hybrid laser/water jet such as is availablefrom SYNOVA Inc., of Lausanne, Switzerland and described in co-filedU.S. Patent Application entitled Tubular Cutting Process and System.

[0048] Where laser 20 is a laser/water jet hybrid, in some embodimentsthe vertical orientation of the tube 12 will help prevent damage to thetube interior as gravity will tend to draw the water column down andthus deflect the laser energy contained therein. Deflection of the laserenergy may be further encouraged by applying a fluid or media flowthrough the tube interior such as is described in greater detail below.

[0049] During the cutting process dross and other debris particles 24are formed. The unique orientation of the tube 12 will assist in theremoval of dross from the tube 12 as gravitational pull will tend todraw the dross downward and out of the tube 12. A flow of fluid, such asa gas, liquid solution, suspension or other media, indicated by arrow 26and hereinafter referred to as a media flow, may be applied to the tubeto further encourage removal of debris 24. Media flow 26 may also act tocool the tube 12 during processing.

[0050] In some embodiments, the media flow 26 is directed through thelumen 28 that the hollow tube 12 defines. Dross and other debrisparticles 24 that extend into the lumen 28 may be caught in the mediaflow 26 and pass through the lumen 28 out the free end 30 of the tube12. In some embodiments waste particles, such as debris 24 may becollected in a filter 32 which allows media flow 26 to pass therethroughfor reclamation or disposal. Filter 32 may also be utilized to receivethe tubular member 12 following processing.

[0051] In some embodiments, media flow 26 may be directed to any portionor surface of the tube 12.

[0052] The vertical orientation of the tube 12 allows system 10 tooperate by using gravity to drive media flow 26 through tube 12.However, if desired media flow 26 may be applied under any desiredpressure.

[0053] As indicated above, in prior horizontal orientation tube cuttingsystems, bowing of the tube during the cutting process may result insignificant damage to the tube resulting in the final stent productbeing improperly cut. The vertical orientation employed by the presentsystem 10 avoids bowing of the tube 12 as gravity will tend to keep thetube in its natural straight orientation. However, it is recognized thatin some cases the free end 30 of the tube 12 or portions thereof, willwhip or oscillate as the tube 12 is spun and moved in accordance withthe predetermined cutting pattern. Such unrestricted movement may bedetrimental to accurate cutting.

[0054] To ensure that such unrestricted movement is minimized orprevented, some embodiments of the present invention include a guidemechanism or collar 40. Guide 40 is a tubular member which defines aguide chamber 42 into which the free end 30 of the tube 12 or a portionthereof, is inserted. Preferably guide 40 is fixedly mounted to asurface of mechanism 10, but in some embodiments the guide may moveablerelative to the tube 12. During processing of the tube 12 the guide 40prevents the free end 30 of the tube 12 from experiencing excessivehorizontal movement outside the scope of the predetermined cuttingpattern.

[0055] In another embodiment shown in FIG. 2, a fluid nozzle 48 may bepositioned adjacent to the guide 40. Nozzle 48 is utilized to injectmedia flow 26 into and/or around tube 12 during processing.

[0056] In some embodiments media flow 26 may also act as a lubricant,oxidizer, cleaner, polishing agent, and/or pretreatment.

[0057] In the embodiments shown in FIG. 2, the media flow 22 directedthrough or adjacent to the guide 40 may replace or be supplementary toother media flows such as have been previously described in relation toFIG. 1.

[0058] Guide 40 may have a variety of configurations and functions. Forexample, in the embodiments shown in FIGS. 3-5 a guide 40 having avariable diameter to accommodate tubes of different diameters is shown.In the embodiment shown, the guide 40 comprises two portions 54 and 56that may be moved toward or away from each other to allow securement ofa tube 12 of a larger diameter or a tube 12 of a smaller diameter withequal ease such as is illustrated in FIGS. 4 and 5 respectively.

[0059] It must noted that the two component configuration of a guide 40shown in FIGS. 3-5 represents merely one embodiment of the guide 40. Asdesired, a variable diameter guide 40 may be equipped with any number ofportions or movement mechanisms. Additionally the guide portions 54 and56 may be provided with a variety of shapes, some examples of which areshown in FIGS. 6-9.

[0060] In FIGS. 6 and 7 a variable diameter guide 40 is shown whereinthe chamber 42 comprises a diamond shape that may be expanded orcontracted in the manner shown.

[0061] In FIGS. 8 and 9 another embodiment of the variable diameterguide 40 is shown wherein a first portion 54 defines a slot 58 intowhich the second portion 56 is inserted to form the chamber 42.

[0062] In yet another embodiment, shown in FIG. 10, the guide 40 maycomprise a wire 60 having one or more coils 62 which define the chamber42 into which the tube 12 is inserted. The coils 62 of the wire may becontracted or expanded merely by increasing or releasing tension on thewire ends 64.

[0063] The above disclosure is intended to be illustrative and notexhaustive. This description will suggest many variations andalternatives to one of ordinary skill in this art. All thesealternatives and variations are intended to be included within the scopeof the claims where the term “comprising” means “including, but notlimited to”. Those familiar with the art may recognize other equivalentsto the specific embodiments described herein which equivalents are alsointended to be encompassed by the claims.

[0064] Further, the particular features presented in the dependentclaims can be combined with each other in other manners within the scopeof the invention such that the invention should be recognized as alsospecifically directed to other embodiments having any other possiblecombination of the features of the dependent claims. For instance, forpurposes of claim publication, any dependent claim which follows shouldbe taken as alternatively written in a multiple dependent form from allprior claims which possess all antecedents referenced in such dependentclaim if such multiple dependent format is an accepted format within thejurisdiction (e.g. each claim depending directly from claim 1 should bealternatively taken as depending from all previous claims). Injurisdictions where multiple dependent claim formats are restricted, thefollowing dependent claims should each be also taken as alternativelywritten in each singly dependent claim format which creates a dependencyfrom a prior antecedent-possessing claim other than the specific claimlisted in such dependent claim below.

[0065] This completes the description of the preferred and alternateembodiments of the invention. Those skilled in the art may recognizeother equivalents to the specific embodiment described herein whichequivalents are intended to be encompassed by the claims attachedhereto.

1. A system for removing material from a tubular member according to apredetermined pattern, the invention comprising orienting the tubularmember in a substantially longitudinal vertical position during removalof the material.
 2. The system of claim 1 further comprising a guidemechanism, the guide mechanism defining a guide chamber, at least aportion of the tubular member being inserted into the guide chamber. 3.The system of claim 1 further comprising a media flow, the media flowbeing a fluid directed on or about the tubular member insertion port. 4.The system of claim 3 wherein the fluid is selected from at least onemember of the group consisting of: a gas, a liquid, a liquid solution, asuspension and any combination thereof.
 5. The system of claim 2 whereinthe guide chamber has a variable diameter.
 6. The system of claim 5wherein the guide mechanism comprises at least two portions, the atleast two portions being moveable relative to one another to provide forthe variable diameter of the guide chamber.
 7. The system of claim 6wherein the at least two portions define a guide chamber having asubstantially circular cross section.
 8. The system of claim 6 whereinthe at least two portions define a guide chamber having a substantiallydiamond shaped cross section.
 9. The system of claim 8 wherein the guidechamber defines an adjustable slot.
 10. The system of claim 1 wherein anend of the tubular member is removably engaged to a securement device,the securement device being engaged to a drive shaft.
 11. The system ofclaim 1 further comprising a laser, the laser constructed and arrangedto transmit laser energy to the tubular member to thereby remove thematerial from the tubular member according to a predetermined pattern.12. The system of claim 10 wherein the laser is selected from at leastone member of the group consisting of YAG lasers, diode lasers, CO₂lasers, IR lasers, UV lasers, laser/water jet hybrids and anycombinations thereof.
 13. The system of claim 1 wherein the tubularmember is constructed at least partially from metal.
 14. The system ofclaim 1 wherein the tubular member is constructed at least partiallyfrom a polymer.
 15. The system of claim 2 wherein the media flow ispassed through the tubular member.
 16. The system of claim 2 wherein themedia flow is constructed and arranged to remove debris buildup withinthe tubular member.
 17. The system of claim 2 wherein the media flow isconstructed and arranged to cool the tubular member during removal ofthe material therefrom.
 18. The system of claim 2 wherein the media flowis selected from at least one member of the group consisting of:lubricants, oxidizers, cleaners, polishing agents, pretreatments and anycombination thereof.
 19. The system of claim 1 wherein the tubularmember is a stent or a component thereof.
 20. The system of claim 1wherein the tubular member is a catheter or a portion thereof.
 21. Amethod for removing material from a tubular member according to apredetermined pattern, the invention comprising the step of orientingthe tubular member in a substantially longitudinal vertical positionduring removal of the material.